Lubricating compositions containing amine salts of boron-containing compounds



United States Patent 3,185,644 LUBRICATING COMPOSITIONS CONTAHNING AMINE SALTS 0F BORON-CONTAINING COMPOUNDS Edwin C. Knowles, Poughkeepsie, N.Y., and Edward L. Kay, Akron, Ohio, assignors to Texaco Inc, New York,

N.Y., a corporation of Delaware No Drawing. Filed Jan. 17, 1961, Ser. No. 83,173

6 Claims. (Cl. 252-336) V and thermally stable in both storage and use. The novel amine salts of the present invention are formed by the reaction of a hydroxy substituted amine and a tri-hydrocarbyl borate and are useful as load carrying additives for mineral and synthetic base lubricating oils.

The present invention is concerned with these novel salts and with their use as lubricating additives. The amine salts of tetra-covalent boron acids of the present invention are known as intra-molecular type salts and are represented by the following general formula:

wherein Risa monovalent hydrocarbyl radical containing one or more carbon atoms to about 30 carbon atoms, R is a divalent hydrocarbylene radical containing 1 to carbon atoms and R" and R' are hydrogen or monovalent hydrocarbyl radicals containing -1 to 24 carbon .atoms. The acid amine salt is present in the lubricating oil in a concentration suflicient to lend load carrying properties to the lubricating oil. The acid 'arnine saltconcentration is usually between 0.05 and 5.0 weight percent.

The term hydrocanbyl when used herein denotes a monovalent hydrocarbon radical and the term hydrocarby-lene when used herein denotes a divalent hydrocarbon radical. a The compositions of the present invennon are prepared by the reaction of a hydroxy substituted amine with a tri-alkyl or -aryl borate to form the intra-molecular substituted aminesalts of the tetra-covalent boron acid.

The hydroxy substituted amines employed in the formation of the novel amine salt of th intra-molecular tetra-covalent boron acids are represented by the formula:

/RII 1E[OR"N RI/I wherein R is a divalent hydrocarbylene radical containing 1 .to 1 0 and preferably 2 to 6' carbon atoms and R and R are hydrogen or a monovalent hydrocarbyl radical containing 1 to 24 and preferably 1 to 8 carbon atoms. Examples of effective hydroxy substituted amines are N- phenyl, N-ethyl aminoethan-ol N,N-diethylaminoethanol,

tC C aminoethanol, octyl aminoisopropanol. octyl aminobutanol and o-aminophenol. V

The intra-molecular tetra-covalent boronacids employed in the formation of the present invention are transitory compounds and as such do not exist in the isolated state. They do, however, form st-able salts. The acids are formed by reaction of a tri-alkyl, or tri-aryl borate with a hydroxy substituted amine which immediately, as the brackets in the equation below indicate, is neutralized by the amine portion thereof to form the salt which may be illustrated by the following general equation:

wherein the values for R, R, R" and R are the same as previously indicated.

The amine salts of the present invention are illustrated by the following: N,N-diethylaminoethylate bore-trimethylate, N-phenyl N ethylaminoethylate 'boro-tri-npropylate N,N-diethylaminoethylate 'boro-tri-n-propylate, octyl aminoethylate bono-tri-n-propylate and t-C -C aminoethylate boro-tri-n-propylate.

The preparation of the specific novel acid amine salts of the tetra-covalent boron acids of the present invention are illustrated in the following examples,

EXAMPLE 1 Preparation of N,N-diethylaminoethylate borotrimethylate 234 grams, 2. 0 mols, N,N-diethylaminoethanol were added to 207 grams, 2.0 mols, tri-met'hyl borate, the pot temperature rose from 27 C. to about 30 C. The reaction product was a clear Water-white liquid.

EXAMPLE 2 Preparation of N-phenyl-N-ethylaminoethylate boro-tri-npropylate 165 grams, 1.0 mol, N-phenyl-N-ethyl-ethanol amine were added to 188 grams, 1.0 mol of tri-n-pnopyl borate, no exothermic reaction took place. The reaction mixture was refluxed for one hour and the reaction product was a clear light amber liquid.

EXAMPLE 3 Preparation of N,N-diethylaminoethy late boro-zri-n- .p p a 117 grams, 1.0 mol, N,N-diethylaminoethano1 were added to 188 grams, 1.0 mol, tri-n-propyl borate, as the aminoethanol was addeda white precipitate formed which dissolved upon further addition of the N,N-diet-hylaminoethanol. The pot temperature rose from 30 to 34 C.

EXAMPLE 4 v Preparation of t-'(C C )amin0ethylate boro-tripropylate grams (0.5 mol) MG -C aminoethanol was added slowly to 86 grams (0.46 mol) of tri-n-propyl borate. The temperature rose from 27 C. to about 30 C, over a fifteen minute addition period. The reaction product was a clear water-White liquid.

The lubricating oils of this invention include hydrocarbon lubricating oils and synthetic lubricating oils. The hydrocarbon oils found to be useful for this invention include oils having'a viscosity in the range required for lubricating fluids and'in particular hydrocarbon mineral oils which include paraflin base, naphthene base, mixed paraffin-naphthene base and mineral oils of the residual or distillate type. The hydrocarbon lubricating base generally has been subjected to solvent refining to improve its oxidation and thermal stability and viscosity-temperature properties as well as solvent dewaxing to. remove esters of hydrocarbyl carboxylic acids.

the oil. Broadly speaking, hydrocarbon lubricating oils having an SUS viscosity at 100 F. of between 50 to 2500 are used in the formulation of the improved lubricants of this invention.

The mineral lubricating oils to which the amine salts of this invention are added usually contain other additives designed to impart desirable properties thereto. For example, viscosity index improvers such as the polymethacrylates having a molecular Weight ranging from 500 to 25,000 are usually included therein. The V1 improver normally used is a polymethacrylate having the following recurring structural unit:

[deni OOOR 11 wherein R is an aliphatic radical ranging from butyl to stearyl and n is an integer of more than 1.

The use of various metal base organic type additives has been found effective and are generally incorporated in the lubricating oils of this invention, particularly those oils used in high speed, spark ignition and diesel engines to reduce ring sticking, minimize lacquer formation and carbon deposits.

The hydrocarbon lubricating oils of this invention may also contain other useful additives such as metal sulfonates to afford additional detergent-dispersant properties, metal dialkyl dithiophosphates to afford additional corrosion and oxidation resistance, anti-foam agents such as silicone polymers in the amount of about 5 to 200 parts per million, etc.

The esters which constituted the synthetic lubricant composition of this invention are broadly described as They are high molecular Weight materials of lubricating oil characteristics derived from alcohols which are usually aliphatic alcohols containing 1 or more hydroxyl radicals and monocarboxylic acids which are usually aliphatic carboxylic acids containing 1 or more carboxylic acid radicals.

Widely used synthetic ester lubricants are aliphatic diesters of aliphatic dicarboxylic acids containing 6 to 12 carbon atoms. From the standpoint of cost and availability, the preferred dibasic acids are adipic acid, sebacic acid and azelaic acid. The aliphatic alcohols used to form the diesters usually contain at least 4 carbon atoms and up to 20 or more carbon atoms. (I -C alcohols are most commonly used. Ether alcohols such as Cellosolve and Carbitolmay also be used in the formation of the aliphatic diesters of organic dicarboxylic acids used as the lubricating base in the compositions of this invention.- Alcohols containing 2 or more hydroxyl radicals and no hydrogen substituted on the beta carbon atom such as triethylol propane and pentaerythritol have proven particularly effective in formulating stable high temperature ester lubricants.

Examples of alkyl esters of aliphatic carboxylic acids are the following: di-isooctyl azelate, di-Z-ethylhexyl sebacate, di-2-ethylhexyl azelate, di-Z-ethylhexyl adipate, dilauryl azelate, di-2-sec-amyl sebacate, di-Z-ethylhexyl alkenyl succinate, di-2-ethoxyethyl sebacate, di-2-(2'- methoxyethoxy) ethyl sebacate, di2(2'-ethylbutoxy) ethyl sebacate, di-Z-butoxyethyl azelate, di-2-(2butoxyethoxy)ethyl alkenyl-succinate, pentaerythritol tetracaproate and trimethylol propane tri-iso-octanoate.

In addition to such esters, polyester lubricants formed by a reaction of an aliphatic dicarboxylic acid, a dihydroxy compound and a monofunctional compound, which is either an aliphatic monohydroxy alcohol or an aliphatic monocarboxylic acid, in specified mol ratios are also employed as the synthetic lubricating base in the compositions of this invention; polyesters of this type are described in U.S. 2,628,974 on Polyester Synthetic Lubricants, which issued to R. T. Sanderson on February 17, 1953. Polyesters formed by reaction of a mixture containing specified amounts of 2-ethyl1,3-hexanediol, sebacic acid, and Z-ethylhexanol and by reaction of a mixture containing adipic acid, diethylene glycol and 2-ethylhexanoic acid illustrate this class of synthetic polyester lubricating bases.

The sulfur analogs of the above-described esters are also used in the formulation of the lubricating compositions of this invention. Dithioesters are exemplified by di- Z-ethylhexyl thiosebacate, di-n-octyl thioadipate and the di-laurate of 1,5-pentanedithiol; sulfur analogs of polyesters are exemplified by the reaction product of adipic acid, thioglycol and 2-ethylhexyl mercaptan.

Alkyl-substituted phenols are usually incorporated in the lubricants of the invention as anti-oxidants. The preferred and most commonly used alkyl phenol anti-oxidants is 2,6-di-tertiary octylphenol; 2,6-di-tertiary amyl-4- methylphenol; and 2,6-di-isopropyl-4-methylphenol. Hindered phenols of this type are employed in concentrations between 0.1 and 1.0 weight percent.

Although hindered phenol type anti-oxidants are the most widely used anti-oxidants in the lubricant compositions of the invention, aryl-substituted amine anti-oxidants such as phenylnaphthylamine, phenylene diamine, and diphenylamine are also used in lubricants in conjunction with the extreme pressure additive of the invention. The amine anti-oxidants are employed in the same concentrations as the hindered phenol anti-oxidant. I

Organic silicones are normally incorporated in the lubricants of the invention to impart thereto anti-foam properties. The silicones are usually of the dialkyl or mixed alkyl-aryl silicone type. Dimethyl silicone is normally employed as the anti-foam agent. The'silicone is incor-- porated in the lubricant by means of a kerosene concen trate containing 5 to 15 Weight percent silicone. A very satisfactory anti-foam agent is a kerosene concentrate 10 Weight percent dimethyl silicone. The kerosene concentrate is employed in an amount sufficient to provide a silicone polymer concentration of from to 250 parts per million based on the total lubricant composition.

To demonstrate the excellent improvement in the load carrying ability of lubricating oil containing the amine salts of the present invention, high speed gear scuff test was used. This test is called the I.A.E. Gear Test and is intended for the evaluation of the load carrying ability or the scuff limited load carrying ability of those lubricants used in reduction and accessory drives of turbo-jet and turbo-prop engines. The I.A.E. Gear Test is one of the requirements of the British Specification D.E.R.D. 2487, Lubricating Oil, Aircraft Turbine Engine, Synthetic Type. The I.A.E. Gear Test is also designed to evaluate the scuff limited, load carrying ability of aircraft gear bydrocarbon lubricants.

The results of the LAB. Gear Test on lubricating oil compositions of the present invention are set forth in the following table:

Table l I.A.E. GEAR TEST Oil: Tooth load, lbs. Base Oil B 20 Base Oil B plus 0.7 wt. percent beta-diethylarninoethanolate boro-tri-n-propylate Base Oil B plus 1.0 wt. percent t-(C -C aminoethanolate boro-tri-n-propylate 105 Base Oil B consisted of a paraffin base crude which has been furfural refined, lightly acid treated, clay contacted and solvent dewaxed and has an SUS viscosity at F. of 150. Table I demonstrates the improvement in the load carrying ability of the base oil when the additives of the present invention are included therein.

As is known in the art many organo borate compounds do not always perform as satisfactory additives for lubri cants, fuel and the like because of their hydrolytic instability and it is to this end that the salts of the present invention demonstrate at least one of their advantages. The amine salt of the intra-molecular tetra-covalent boron all-ls a was) (R0 B OR'N+HRR" wherein R is a monovalent hydrocarbyl radical containing one carbon atom to about 30 carbon atoms, R is a divalent hydrocarbylene radical containing 1 to 10 carbon atoms and R" and R' are selected from the group consisting of hydrogen and a monovalent hydrocarbyl radical containing 1 to 24 carbon atoms.

2. A lubricating oil as described in claim 2 containing 0.5 to 5.0 weight percent of an amine salt having the formula:

(C2H5 2N+HCH2CH2OB (OCH3 3 3. A lubricating oil as described in claim 2 containing a 0.5 to 5.0 weight percent of an amine salt having the formula:

4. A lubricating oil as described in claim 2 containing 0.5 .to 5.0 weight percent of an amine salt having the formula:

(CZHS)2N+H CH2CHZO B -(OC3HT)3 5. A lubricating oil as described in claim 2 containing 6 0.5 to 5.0 weight percent of an ammonium salt having the formula:

wherein R is an alkyl group containing 11 to 14 carbon atoms.

6. A lubricating oil composition comprising a mineral lubricating oil and 0.05 to 5 .0 Weight percent of an amine salt of a tetra-covalent boron acid having the general formula:

wherein R is a monovalent hydrocarbyl radical containing 1 to about 30 carbon atoms, R is a divalent hydrocarbylene radical containing 1 to 10 carbon atoms and R" and R are selected from the group consisting of hydrogen and a monovalent hydrocarbyl radical containing 1 to 24 carbon atoms.

References Cited by the Examiner UNITED STATES PATENTS 2,312,208 2/43 Clayton et al 25233.6 2,582,191 1/52 Curtis 260462 2,629,732 2/53 Schechter 260 -462 2,795,547 6/57 Harle et a1. 252-496 2,795,548 6/57 Thomas et al. 25249.6 2,957,840 10/60 Groszos et a1. 260-462 X DANIEL E. WYMAN, Primary Examiner.

JULIUS GREENWALD, Examiner. 

1. A LUBRICATING OIL CONTAINING AN AMINE SALT OF A TETRACOVALENT BORON ACID IN AN AMOUNT SUFFICIENT TO IMPROVE THE LOAD CARRYING PROPERTIES THEREOF, SAID AMINE SALT HAVING THE FOLLOWING GENERAL FORMULA: 